Typically, drainage catheters are tubular, flexible conduits percutaneously inserted into a fluid collection within the viscera. Common applications of drainage catheters include abscess, biliary, and nephrostomy drainage resulting from the body's temporary inability to naturally drain these fluid collections. A drainage catheter may be introduced over a stiffening cannula using either a direct trocar stick or a Seldinger technique, over a guidewire.
To inhibit catheter movement, a pigtail loop or other retention structure is often formed at the catheter's distal end. The loop, once formed, engages surrounding tissue, such as the inner walls of a lumen or organ, preventing the catheter from displacing due to accidental tugging or pulling.
Some catheters include a pre-formed pigtail loop at their distal end. Before placing this catheter in the body, a rigid wire is inserted to straighten out the loop. Once placed, the rigid wire is removed. Alternatively, the pigtail loop may be formed after the instrument is inserted at the desired location. In such catheters, a suture, fixed to the catheter's distal end, extends along the catheter's length, and exits from its proximal end. By drawing the suture proximally, the distal tip of the catheter is forced to curl into a pigtail formation. A proximal suture portion is then secured to hold it in place and retain the loop shape at the distal end of the catheter.
Many such lockable pigtail loop catheters are available today. Some lockable catheters include a locking mechanism that requires a separate unlocking tool. If the unlocking tool is misplaced, it may be difficult to release such sutures and disengage the catheters. Other lockable catheters do not require external unlocking tools, rendering them susceptible to being inadvertently unlocked.
Therefore, there remains room for improvement and/or alternatives in providing tamper-resistant structures for drainage catheters.